Electric arc working torch

ABSTRACT

A front design for electric arc working torches featuring at least one sleeve of electrically insulating material surrounding the torch body and insulating such body from the nozzle, and a clamp and nozzle arrangement such that upon heating of such member they are brought into tighter contact increasing heat transfer thereacross.

United States Patent nan 4 1 Sept. 5, 1972 [54] ELECTRIC ARC WORKINGTORCH [72] Inventor: Clifford Warren Hill, Pleasantville,

[73] Assignee: Union Carbide Corporation, New

York, N.Y.

[22] Filed: Sept. 9, 1970 [21] Appl. No.2 70,800

[52] US. Cl. ..2l9/130, 219/74, 219/136 [51] Int. Cl. ..B23k 9/00 [58]Field of Search ..219/l30, 74, 136

[5 6] References Cited UNITED STATES PATENTS Borneman ..219/136 x3,283,121 11/1966 Bernard et al. ..2l9/l30 3,541,298 ll/l970 Carkhuff....2l9/l 30 3,469,070 9/1969 Bernard et al. ..219/ 130 PrimaryExaminer-J. V. Truhe Assistant Exam'inerHugh D. Jaeger Attorney-Paul A.Rose, Harrie M. Humphreys and Dominic J. Terrninello [57] ABSTRACT Afront design for electric arc working torches featuring at least onesleeve of electrically insulating material surrounding the torch bodyand insulating such body from the nozzle, and a clamp and nozzlearrangement such that upon heating of such member they are brought intotighter contact increasing heat transfer thereacross.

8 Claims, 1 Drawing figure ELECTRIC ARC WORKING TORCH Torch designincorporating conventional means for electrically insulating and coolingthe nozzle of such torches has been complex, difficult and expensive tomanufacture, heavy and difficult to repair. Recently R.

M. Gage in US. Pat. application Ser. No. 600,569, now US. Pat. No.3,524,040 discovered a method for designing electric arc working torchesusing a thin film of high thermal conductive material whichsatisfactorily conducted heat from the nozzle to the torch body whilemaintaining electrical insulation therebetween.

This invention is an improvement in, the Gage concept and produces apractical application of the principal disclosed by Gage.

Accordingly, it is a main object of this invention to provide a novelfront end design for electric are working torches which is simple,inexpensive to manufacture and easy to repair.

It is a more specific object to provide a welding torch of such design.

These and other objects will become apparent or will be pointed out withreference to the following description and drawings wherein the soleFIGURE is a view partially in cross-section of the preferred embodimentof the invention.

in the drawing, the torch T comprises a water cooled body or heat sink12. Separating the heat sink 12 from the slotted nozzle 14 is anelectrically insulating sleeve 16. The slotted nozzle is preferably madefrom copper or aluminum alloy and abuts against a nozzle insulator 13.Nozzle insulator 13, in addition to insulating the nozzle, serves as ashock adsorber when a welder strikes the nozzle against a plate toremove adhering spatter from the nozzle, for example. In the embodimentshown, two sleeves are utilized. These sleeves have a wall thickness ofpreferably about 0.020 inches, although thicker sections up to aboutone-sixteenth inch may be used, and are made of anodized aluminum, thusproviding in effect four electrically insulating surfaces. The anodizingprocess converts the outside surface of the aluminum sleeves to aluminumoxide, thus forming an insulating coating that is an integral part ofthe sleeve. This has the advantage that it is less susceptible tochipping than coating which is sprayed on. The preferred anodizingprocess usually forms a 0.003 $0.001 inch thick conversion coating onthe aluminum surfac The nozzle 14 is slotted .and is externally clampedby clamping means 18 to the insulating sleeves 16. This arrangementeliminates the nozzle threads which, of course, have a limited life andresult in a relatively high thermal resistance due to an accumulation ofabrasive spatter in the threads which results in higher nozzletemperatures. A basic objective of the invention is to reduce nozzletemperatures.

Depending from the body 12 is a copper alloy contact tip 20 which isusually concentrically spaced from the interior of the nozzle 14 toprovide an annular passage 22 from the flow of gas or gas mixtures outof the torch T.

A consumable wire electrode is fed through the torch T to the contacttip 20 where it picks up welding current fed to the contact tip from awelding power source.

In the embodiment described, the sleeves 16 are approximately 2 incheslong and extend into the nozzle 14. Accordingly, a large percentage,approximately 57 percent in the embodiment shown,'of the inside diameterof the nozzle which would receive direct radiant heat from the arc andweld puddle is shielded by the sleeves from receiving direct radiantheat from the arc and weld puddle. The percentage would vary withdifferent size nozzles.

Because of the clamp and nozzle arrangement in this invention, thermalexpansion results in tightening of the joints and improved heattransfer. The external clamp 18 is made from a material (stainless steelpreferably) which has a lower coefficient of thermal expansion than thenozzle material, the anodizedaluminum sleeves and the copper alloy body,thus higher temperatures result in a tightening effect when thesefactors are combined with the slots in the nozzle and anodized sleeves.

Also, because of the slots in the nozzle and the anodized sleeves, incombination with the external clamping means, it is possible todimension the mating diameters for virtually a perfect fit, whichincreases heat transfer.

It is preferred to use anodized aluminum sleeves as the insulatingsleeves. With the high thermal conductivity of the aluminum oxideanodized coating, the total calculated temperature drop across the fourthin film anodized coatings is in the order of only 11F. when operatingat 350 arnperes with 95 percent argon and 5 percent oxygen shieldinggas. The 11F. temperature drop across the sleeves indicates thatefficient heat transfer is occurring thereacross.

While anodized aluminum is preferred, various other insulation coatingmaterials would be suitable for manufacture of the insulating sleeves.These include beryllium oxide, magnesium oxides, zirconium silicate,borosilicate glass, boron nitride magnesium aluminate and mica, forexample. Generally, materials are unsatisfactory if they have a thermalconductivity of less than 0.005 watts/in /F./in. from F. to 400F. whichwould include materials such as fluorocarbon resins, the most well knownbeing Teflon. However, it is possible to coat the thin anodized aluminumwith a very thin coating of Teflon, preferably with less than 0.0005inch thickness to minimize the possibility of failure of the electricalinsulation.

What is claimed is:

1. A gas shielded electric are working torch comprising an electricallyconductive torch body having a heat sink therein;

at least one sleeve of electrically insulating material surrounding saidtorch body and in intimate contact therewith, said electricallyinsulating material having a thermal conductivity of at least 0.005wattslin lFjin. from 70F. to 400F.;

a slotted threadless nozzle mounted on said sleeve;

and clamping means securing said nozzle to said sleeve whereby saidnozzle and said sleeve can be tightened to ensure intimate contacttherebetween. 2. Torch according to claim 1 wherein said sleeve isslotted to ensure intimate contact between said torch body and saidsleeve.

3. Torch according to claim 1 wherein said sleeve is approximately twoinches long and covers approximately 57 percent of the inside surface ofsaid nozzle that would receive direct radiant heat from the'arc and weldpuddle.

4. Torch according to claim 1 wherein said sleeve is made of aluminumwith an anodized coating.

5. Torch according to claim 1 wherein two sleeves are used.

6. Torch according to claim 5 wherein each sleeve has a wall thicknessof approximately 0.020 t 0.0015 and an anodized coating in each surfaceof each sleeve of approximately 0.003 t 0.001 thick.

7. A torch according to claim 1 wherein a contact tip is connected insaid torch body for the passage of a consumable electrode therethrough.

8. A torch according to claim 1 wherein said clamping means have a lowercoefficient of thermal expansion than said slotted threadless nozzle.

1. A gas shielded electric arc working torch comprising an electricallyconductive torch body having a heat sink therein; at least one sleeve ofelectrically insulating material surrounding said torch body and inintimate contact therewith, said electrically insulating material havinga thermal conductivity of at least 0.005 watts/in2/*F./in. from 70*F. to400*F.; a slotted threadless nozzle mounted on said sleeve; and clampingmeans securing said nozzle to said sleeve whereby said nozzle and saidsleeve can be tightened to ensure intimate contact therebetween. 2.Torch according to claim 1 wherein said sleeve is slotted to ensureintimate contact between said torch body and said sleeve.
 3. Torchaccording to claim 1 wherein said sleeve is approximately two incheslong and covers approximately 57 percent of the inside surface of saidnozzle that would receive direct radiant heat from the arc and weldpuddle.
 4. Torch accorDing to claim 1 wherein said sleeve is made ofaluminum with an anodized coating.
 5. Torch according to claim 1 whereintwo sleeves are used.
 6. Torch according to claim 5 wherein each sleevehas a wall thickness of approximately 0.020 + or - 0.0015 and ananodized coating in each surface of each sleeve of approximately 0.003 +or - 0.001 thick.
 7. A torch according to claim 1 wherein a contact tipis connected in said torch body for the passage of a consumableelectrode therethrough.
 8. A torch according to claim 1 wherein saidclamping means have a lower coefficient of thermal expansion than saidslotted threadless nozzle.